2nd generation PLA; Lactide formation directly from aqueous lactic acid

Catalysis Communications, vol. 177, pp. 106636

Abstract

In order to develop a 2nd generation polylactic acid (PLA) process, lactide (LD) was synthesized directly from a commercially available 90% aqueous lactic acid (LA) solution. Experiments were conducted in an ordinary continuous flow fixed bed reactor. The reaction was carried out over various zeolites and γ-Al2O3 catalysts. Furthermore, the influence of pressure, temperature and water content in the inlet was studied. The highest LD selectivity of 98.9% was obtained using 90% LA and γ-Al2O3 as catalyst. In addition, it is concluded that LD yield increases when using highly concentrated LA oligomer with a minor amount of water. The catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray powder diffraction (XRD), nitrogen adsorption isotherms (BET), temperature programmed desorption of ammonia (NH3-TPD) and pyridine Fourier transformed infrared spectroscopy (Py-FTIR).

Authors 3

1. Moritz Venschott corresponding Aachen Formerly Department of Chemical Technology and Heterogeneous Catalysis

   RWTH Aachen University · IU International University of Applied Sciences

   Affiliation as printed

   Formerly Department of Chemical Technology and Heterogeneous Catalysis, RWTH Aachen University, Worringerweg 1, Aachen D-52074, Germany

   IU Internationale Hochschule, Juri-Gagarin-Ring 152, Erfurt D-99084, Germany

2. Wolfgang F. Hoelderich Aachen Formerly Department of Chemical Technology and Heterogeneous Catalysis

   RWTH Aachen University

   Affiliation as printed

   Formerly Department of Chemical Technology and Heterogeneous Catalysis, RWTH Aachen University, Worringerweg 1, Aachen D-52074, Germany

   TCHK Hoelderich Consultancy, Frankenthal, Germany

3. Matthias Eisenacher Aachen Formerly Department of Chemical Technology and Heterogeneous Catalysis

   RWTH Aachen University · TH Köln - University of Applied Sciences

   Affiliation as printed

   Circular Transformation Lab Cologne, TH Köln-University of Applied Sciences, Köln 50678, Germany

   Formerly Department of Chemical Technology and Heterogeneous Catalysis, RWTH Aachen University, Worringerweg 1, Aachen D-52074, Germany